SU1041226A1 - Method of automatic compensation of metal cutting machine spindle displacements - Google Patents

Abstract

A METHOD FOR AUTOMATIC COMPENSATION OF HEAT DISPLACEMENTS OF A SPINDLE METAL CUTTING MACHINE WITH A NUMBERING programmed control, which consists in determining the values of the spindle thermal displacements in the process and introducing a correction in the movement of the working bodies of the machine along the controlled coordinate axes, which are different, in the case of the machining of the working bodies of the machine using controlled coordinate axes, in the case of the displacement of the working bodies of the machine on the controlled coordinate axes, in the case of the machining of the working bodies of the machine on the controlled coordinate axes, in the case of the machining of the working bodies of the machine on the controlled coordinate axes, in the case of the machining of the working bodies of the machine on the controlled coordinate axes, in the case of the machining of the working bodies of the machine on the controlled coordinate axes, the systems are different in the process of the spindle, and the correction of the movement of the working bodies of the machine along the control axes of the spindle is different. The type and parameters of the functions of the thermal displacement of the machine spindle are determined for each frequency of its rotation, and with just x and according to the determined functions, the processing calculates the magnitude of the thermal displacement of the spindle depending on the operating time (/) at different rotational frequencies, as well as from time is simple, and at the moments of reaching the calculated values of the established allowable values, the movement of the executive bodies of the machine is corrected. Yu you se

Description

The invention relates to machine tools and can be used in all areas of the national economy to automatically compensate for the heat output of various machines. There is a known method of automatically adjusting the position of the working bodies of the machine tools by redistributing the internal deformations of the body members carrying the working parts of the machine and subjected to heating or cooling depending on the deviations of the working bodies ll. The disadvantages of this method are the need to continuously measure the deviations of the working bodies due to thermal deformations, the presence of controlled heating and cooling devices and a complex control system of these devices, as well as the impossibility of fully simultaneously compensating for the deviations of the working bodies in three mutually perpendicular directions. A known method for compensating thermal deformations of CNC metal cutting machines, consisting in a constant measurement of the heating temperature at a characteristic point on the machine and a subsequent displacement of the working parts in proportion to the change in the measured temperature ts. The disadvantages of this method are the need to experimentally determine the characteristic point for measuring the heating temperature, the need constant measurement of the heating temperature at this point and the impossibility of complete and at the same time compensating for thermal deformation s in three mutually perpendicular directions over the entire frequency range of the spindle rotation. There is also known a method of co-compensation of thermal deformations of metal-cutting machine tools, which consists in a constant measurement of the heating temperature at characteristic points on the machine, followed by calculation based on the measurement of deviations of the working bodies due to thermal deformations in three views of the perpendicular directions and the corresponding displacement of workers bodies when operating the machine Z. The shortcomings of this method are the complexity and lack of accuracy due to the need to experimentally determine the characteristic points for LOAD temperature and the nature of va interconnecting these tempergure .teplovymi with strain E as well as the necessary measuring constant heating temperature in these characteristic points when working cfa} i ka. A common disadvantage of these methods is that they do not take into account the nature of the change in thermal deformations of the working bodies in three mutually perpendicular directions, as well as the different nature of thermal deformations at different frequencies of rotation of the spindle and at its simple x. The aim of the invention is to simplify and improve the accuracy of automatic compensation of the thermal displacements of the spindles of numerically controlled machine tools with numerical control (CNC) for all controlled axes without measuring the thermal displacements of the spindle during operation of the CNC machine. This goal is achieved by the fact that according to the method of automatic compensation of thermal displacements of the spindle of a machine tool with numerical control, which consists in determining the values of thermal displacements of the spindle during processing and introducing a correction in the movement of the working parts of the machine along controlled axes, they determine the type and parameters functions of the thermal displacement of the spindle of the machine for each frequency of its rotation and with just x and according to certain functions, when processing, Depending on the operating time at different rotational frequencies, as well as from time, the spindle moves are simple, and at the moments when the calculated values of the set allowable values are reached, the movement of the machine actuators is corrected. The method is based on the fact that iz-. The change in the thermal displacements of a spindle of a mei-cutting machine tool with a CNC takes place according to several well-defined typical functions characteristic of a given structural-design solution of a machine with a CNC and for certain rotational frequencies. At the same time, in one CNC machine for different directions of coordinate axes, the thermal displacements of the spindles vary according to different typical functions. Having determined the type and parameters of the change of thermal deformations of the spindle displacements for a particular machine, in three mutually perpendicular directions, according to known rotation frequencies the spindle during the operation of the machine and the operating time at these frequencies is used to calculate the obtained values of the thermal displacements of the spindle in accordance with the functions known for this machine to change them and automatically and shift the working bodies of the machine in the same direction and by the same amount, i.e. The relative position of the working parts of the machine is constantly maintained. When the spindle stops rotating when the machine is cooling,

Knowing the function of changing the spindle thermal displacements during cooling of this machine and the cooling time, the spindle reverse displacement values are calculated during cooling, followed by automatic compensation of this displacement by moving the working bodies in another direction.

Figure 1 shows a typical dependence of the thermal displacements of time t; in fig. 2. and 3 are examples of block diagrams of devices for implementing the method.

Referring to Fig. 1, an application is shown of the method for automatically compensating for thermal displacements of a CNC cutting machine spindle, for which typical functions of changing thermal displacements for different spindle rotation frequencies during heating and cooling of the machine are defined.

Consider the process of automatic compensation of thermal displacements, spindles when machining one part from the moment the machine turns on at spindle speeds n, n 2 and n, respectively, for a time t., T 3 5 cooling the machine when switching spindle speeds and changing tools with time t and t, and when removing the finished part in the installation of the workpiece with a time t.

 Automatic compensation of thermal displacements of the spindle is carried out periodically through the value D established for each controlled axis of coordinates, both during heating and cooling of the machine. The value of L is determined based on the required accuracy of processing.

When the machine is started up and the part is machined at the spindle rotation frequency and the spindle thermal deformations vary according to the typical function 1 (Fig. 1). Upon reaching the magnitude of the thermal displacements; -equivalence e, they are compensated by the corresponding displacement of the working member. After time t., The spindle rotation frequency is switched to n t at which the thermal displacements of the spindle are already changed according to the type function 2 (Fig. 1). During the switching time t, the spindle does not rotate and cooling occurs according to the typical function 4. When operating at frequency n a further thermal displacement of the spindle takes place according to the typical function 2, and when this displacement value is equal to L-, they are also compensated. Similarly, automatic compensation is performed when operating at a spindle speed n, when the thermal displacement of the spindle occurs according to the typical function 3.

When removing the finished part and installing the workpieces, the spindle does not rotate, and the machine cools and the spindle shifts according to typical function 4 for a time of 5 tg. When the spindle is displaced due to the cooling of the machine by the value of d., This displacement is compensated by moving the working member by the amount of 4 in the opposite direction.

When the machine continues to work, the thermal displacements of the spindle are produced in an analogous way.

The device that implements the method

5 automatic compensation of thermal displacements of the CNC machine spindle, consists (figure 2) of the sensor 1 for determining the rotational speed, unit 2 for setting the standard functions of the thermal

0 displacement, spindle on the control axes of the coordinate axes, block 3 setting the step size of the performed correction on the controlled axes of the coordinates of the cutting machine 4 with the device

5 numerical control 5, built on the basis of a mini-computer (SNS-class device) and block b of determining the time of work of the machine at a given spindle speed

0 or no spindle rotation time when cooling | Machine;

i In the case when the CNC device 5 (FIG. 3) of the cutting machine 4 is not built on the basis of a mini-computer (device of class NC), the mini-computer 7 is additionally introduced to it along with the above blocks 1–4 (figure 2) (fig.Z). All of them are interconnected by electrical circuits.

Device for automatic compensation of thermal displacements of spindle CNC machine tools

c works as follows (figure 2),

The spindle speed information entered into the CNC device 5 with a punched tape is detected by sensor 1 and transmitted to the mini-computer memory of the CNC device 5,

0 where information about the time of rotation of the spindle at a given frequency, determined from the information entered by a punched tape, also arrives from block 6. Mini-computer CNC device 5 on

5, based on the data received from sensor 1 and block 6, selects from block 2 pre-defined typical functions of thermal spindle displacements characteristic of this

0 of a CNC cutting machine with the corresponding coordinate axes at a given spindle speed. By . information from sensor 1 and block b, in accordance with the typical function extracted from block 2, the mini-computer of the CNC device 5, determines the values of the thermal spindle displacement along the corresponding coordinate axes successively through small and equal intervals of time. The obtained values of thermal displacements are compared with the value characterizing the step of coordination carried out, which is set along each coordinate axis by block 3. When the thermal displacement of the spindle reaches the equalization step, the CNC device 5 sends a signal to the additional displacement of the working parts of the machine, which ensures a constant maintaining their mutual relative position. In the second case, when the CNC device does not contain a mini-computer (Fig. 3), the information from blocks 1-4 enters the additionally inserted mini-computer 7 connected to the CNC device 5 by an electrical circuit. The operation of the device for automatic compensation of thermal displacements of the spindle is similar to that described. The use of the present invention allows improving the accuracy of machining parts on metal-cutting machines with CNC by automatically compensating for thermal displacements of the spindle simultaneously over all controlled coordinate axes without creating and using additional measuring means disposed on the CNC machine. This increases the efficiency of using CNC machine tools - it allows them to process more precise parts from one plant, which shortens the overall technological cycle of processing these parts, and increases the productivity of processing.

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Claims (1)

METHOD FOR AUTOMATIC COMPENSATION OF HEAT DISPLACEMENTS OF THE SPINDLE OF THE METAL-CUTTING MACHINE with NUMERICAL program control, which consists in establishing the values of the thermal displacements of the spindle during processing and introducing correction in the movement of the working bodies of the machine along the controlled coordinate axes, which is simplified by the fact that accuracy, determine the type and parameters of the thermal displacement functions of the machine spindle for each frequency of its rotation. spindle thermal displacement ranks depending on the operating time at various speeds, as well as the idle time, and the calculated arrival times of permissible values established by the adjustment movement is performed executive organs of the machine.